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Abstract Extracellular vesicles (EVs) are small, membrane-bound structures released by cells. They contain various biomolecules and have emerged as mediators of cellular signaling. EVs of various origins can be isolated from body fluids and hold potential as novel biomarkers. However, their clinical implementation as biomarkers is hampered by complex isolation procedures, limited expertise in routine labs, and a lack of mechanistic understanding of signal transfer, particularly in vivo. To better understand how EVs carry oncogenic signaling factors, we performed mechanistic investigations into the role of EVs in WNT signaling as a representative cancer-associated signaling pathway, as well as ex vivo validation experiments analyzing patient-derived EVs. Hydrophobic WNT ligands can use EVs to travel the extracellular space. However, little is known about the quantities of WNT secretion onto different EV fractions and potentially other vehicles. To explore WNT secretory routes and potential functional differences, we generated fluorescently tagged marker constructs of the non-canonical ligand WNT5a, which has context-dependent tumor-suppressing or -promoting functions in cancer. In additional in vitro experiments, we tested how the WNT signaling activation state and cancer-specific WNT mutations, such as CRISPR/Cas9-induced APC truncations, quantitatively and qualitatively affect EV shedding in colorectal cancer cell lines. Further functional testing of EV-bound vs. non-EV WNT ligands is ongoing. For proof-of-concept analyses and to test EVs as biomarkers, we set up the liquid biopsy study EValuate. The project aims for cross-entity analysis of EV profiles and correlation of results to cancer presence, stage, and survival. For quality control and before pipeline implementation, we tested various EV isolation methods and compared different sample pre-processing steps. By combining multidisciplinary expertise in biophysics, molecular biology, and basic and clinical cancer research, we aim to gain a better mechanistic understanding of EV-mediated signal transfer and facilitate the integration of EVs as diagnostic and prognostic biomarkers into clinical studies. Citation Format: Antonia Schubert, Nadine Winkler, Ajaree Mongkolsittisilp, Matthias Schulz, Oksana Voloshanenko, Meike Schaffrinski, Dominique Kranz, Karin Nienhaus, Dirk Jäger, Lorenz Trümper, Judith Büntzel, Claudia Binder, Gerd Ulrich Nienhaus, Michael Boutros. Extracellular vesicles as carriers of signaling factors in cancer abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 6968.
Schubert et al. (Fri,) studied this question.